I never ended up in Florean's so not sure - but got a huge scoop (maybe double scoop?) at Ben & Jerry's for a snack credit. Most of my snack credits went on cheesecakes from the Boulangerie. They are ginormous and IMO, just as good as the ones from the Cheescake Factory. We would also use snack credits for a frozen butterbeer 1x a trip.
For drinks, you can get fresh-squeezed lemonade at a cart somewhere (I think in front of Rip Ride Rockit). Also in Leaky Cauldron you can get pumpkin fizz or various ciders (my preferred use for drink credits). If you want a bottle of water, there are bigger bottles in the Simpsons Quick Service food court. You can also get small coffees in either Starbucks. My DH likes the bottled frappucinos so we got a bunch of those to bring home with leftover drink credits one time. The Starbucks in Citywalk are great at handling credits and have a small menu to show you your options. The Starbucks in the park had no clue, wouldn't let me buy a bottled frapp and took forever and a day to process my credits (nice people who tried hard - but none were trained on handling credits). Odd that it wasn't the other way around.
Also, I'm sure you've already discovered from your research that it is best to wait until you want to order an expensive entree to pay for the quick service plan. And that you can buy them one at a time (each valid for 1 entree, 2 drinks, and 1 snack), do not need to buy them for your whole party, and that they are valid for something like 14 days. Be aware that you could be juggling a lot of cards (only 1 day of the dining plan is loaded onto each card).
Have fun!
